Question

我必须像下面这样的链接一样构建一棵树http://bl.ocks.org/robschmuecker/7880033，

我需要在 sqlserver 数据库中生成分层 json 数据，我曾尝试使用递归函数，但由于递归函数在 sql server 中具有 max limit32，我无法继续使用该函数，其中我有大量与上述相同的数据URL，树是完全动态的，下面是我的表结构

CREATE TABLE #dndclasses
(
   id         INT  IDENTITY PRIMARY KEY,
   parent_id  INT,
   name       TEXT
);



INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (1, 0, N'Tom')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (2, 0, N'Josh')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (3, 1, N'Mike')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (4, 1, N'John')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (5, 2, N'Pam')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (6, 2, N'Mary')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (7, 3, N'James')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (8, 3, N'Sam')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (9, 4, N'Simon')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (10, 4, N'QQom')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (11, 4, N'QQosh')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (12, 6, N'QQike')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (13, 6, N'QQohn')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (14, 7, N'QQam')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (15, 7, N'QQary')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (16, 8, N'QQames')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (17, 8, N'QQam')
INSERT [dbo].[dndclasses] ([id], [parent_id], [name]) VALUES (18, 4, N'QQimon')

非常感谢任何帮助，并提前致谢

基本上我几乎需要像这样的分层查询

https://tapoueh.org/blog/2018/01/exporting-a-hierarchy-in-json-with-recursive-queries/

但以上是在 postgre sql 中，我必须在 sql server 中实现相同的

预期产出

[{
  "id": 1,
  "parent_id": 0,
  "name": "Tom",
  "Children": [{
    "id": 3,
    "parent_id": 1,
    "name": "Mike",
    "Children": [{
      "id": 7,
      "parent_id": 3,
      "name": "James",
      "Children": [{
        "id": 14,
        "parent_id": 7,
        "name": "QQam"
      }, {
        "id": 15,
        "parent_id": 7,
        "name": "QQary"
      }]
    }, {
      "id": 8,
      "parent_id": 3,
      "name": "Sam",
      "Children": [{
        "id": 16,
        "parent_id": 8,
        "name": "QQames"
      }, {
        "id": 17,
        "parent_id": 8,
        "name": "QQam"
      }]
    }]
  }, {
    "id": 4,
    "parent_id": 1,
    "name": "John",
    "Children": [{
      "id": 9,
      "parent_id": 4,
      "name": "Simon"
    }, {
      "id": 10,
      "parent_id": 4,
      "name": "QQom"
    }, {
      "id": 11,
      "parent_id": 4,
      "name": "QQosh"
    }, {
      "id": 18,
      "parent_id": 4,
      "name": "QQimon"
    }]
  }]
}, {
  "id": 2,
  "parent_id": 0,
  "name": "Josh",
  "Children": [{
    "id": 5,
    "parent_id": 2,
    "name": "Pam"
  }, {
    "id": 6,
    "parent_id": 2,
    "name": "Mary",
    "Children": [{
      "id": 12,
      "parent_id": 6,
      "name": "QQike"
    }, {
      "id": 13,
      "parent_id": 6,
      "name": "QQohn"
    }]
  }]
}]

Answer 1

递归方法是解决您的需求的最佳实践；但是，我在下面分享的这个查询仅适用于三级层次结构（基于示例数据的性质）。虽然，如果您的树有超过三个嵌套对象，您需要采用自动递归的方法：

SELECT Parent.id, Parent.name,
    (SELECT c.id, c.name,
        (SELECT cc.id, cc.name
         FROM #dndclasses cc
         WHERE cc.parent_id = c.id FOR JSON PATH) as ChildOfChilds
     FROM #dndclasses c
     WHERE c.parent_id = Parent.id FOR JSON PATH) as Childs
FROM #dndclasses Parent
WHERE Parent.parent_id = 0 FOR JSON PATH

如果可能，请给我们反馈。

在没有递归函数的情况下在sql server中生成分层json

1 个答案: